GDScript: Fix some export annotation issues #30230

Job	Run time
📊 Static checks / Code style, file formatting, and docs	28s
🍎 macOS / Editor (target=editor, tests=yes)	4m 3s
🏁 Windows / Editor (target=editor, tests=yes)	7m 22s
🍎 macOS / Template (target=template_release)	3m 4s
🏁 Windows / Template (target=template_release)	8m 4s
🍏 iOS / Template (target=template_release)	2m 21s
🐧 Linux / Editor w/ Mono (target=editor)	3m 41s
🐧 Linux / Editor with doubles and GCC sanitizers (target=editor, tests=yes, dev_build=yes, scu_build=yes, precision=double, use_asan=yes, use_ubsan=yes, linker=gold)	13m 44s
🌐 Web / Template w/ threads (target=template_release, threads=yes)	3m 45s
🐧 Linux / Editor with clang sanitizers (target=editor, tests=yes, dev_build=yes, use_asan=yes, use_ubsan=yes, use_llvm=yes, linker=lld)	6m 24s
🌐 Web / Template w/o threads (target=template_release, threads=no)	3m 47s
🐧 Linux / Editor with ThreadSanitizer (target=editor, tests=yes, dev_build=yes, use_tsan=yes, use_llvm=yes, linker=lld)	6m 11s
🤖 Android / Template (target=template_release)	3m 27s
🐧 Linux / Template w/ Mono (target=template_release)	54s
🐧 Linux / Minimal template (target=template_release, everything disabled)	1m 17s
🪲 Godot CPP / Build and test Godot CPP	7m 13s
	1h 15m 45s

Provide feedback